The heterotrophic plate count (HPC), formerly known as the standard plate count, is a procedure for estimating the number of live heterotrophic bacteria in water. This test can provide useful information about water quality and supporting data on the significance of coliform test results. High concentrations of the general bacterial population may hinder the recovery of coliforms .The HPC is useful in judging the efficiency of various treatment processes for both drinking water and swimming pools, and for checking the quality of finished water in a distribution system.